1. Field of the Invention
This invention relates to polymeric dispersant additives for lubricants and hydrocarbon fuels. When of higher molecular weight, the additives are also useful as viscosity index improvers for lubricants.
More particularly, this invention relates to hydrocarbon polymers such as tertiary hydrogen-containing or alpha olefin polymers and, in particularly, ethylene copolymers having a degree of crystallinity of less than about 25 weight percent as determined by X-ray or differential thermal analyses and comprising from about 2 to 98 parts by weight of ethylene and one or more C.sub.3 to C.sub.28 alpha olefins, usually propylene, which have been reacted with an oxygen-containing gas and an amine compound at an elevated temperature of at least about 130.degree. C. to form an aminated polymeric reaction product.
2. Description of the Prior Art
A variety of polymeric materials which incorporate nitrogen have been described in U.S. and foreign patents as dispersants for fuels and lubricants, and as viscosity index improvers for lubricants. For example:
U.S. Pat. No. 3,404,091 grafts polar monomers, such as acrylonitrile onto hydroperoxidized copolymers of ethylene and propylene.
U.S. Pat. No. 3,404,092 reacts hydroxylated ethylenepropylene copolymers with isocyanates.
U.S. Pat. No. 3,687,849 grafts various unsaturated monomers onto a degraded, hydroperoxidized, interpolymer of ethylene and propylene.
U.S. Pat. No. 3,769,216 shows an atactic (i.e., non-crystalline) copolymer of ethylene and propylene containing from 45 to 65 mole percent of ethylene, mechanically degraded in the presence of oxygen, followed by reaction with a polyamine.
U.S. Pat. No. 3,785,980 discloses the reaction product of an amine with a hydroperoxidized atactic copolymer of ethylene and propylene containing from 45 to 65 mole percent of ethylene.
U.S. Pat. No. 3,756,954 discloses the oxidation and degradation of interpolymers and in particular ethylene and propylene copolymers by heating them above 100.degree. C. with an oxygen-containing gas, usually air in the presence of an aliphatic amine which amine serves as a color stabilizer under the conditions of the reaction and is present in an amount of from about 1 to 5 percent based upon the weight of the polymer being degraded.
British Pat. No. 1,172,818 describes the preparation of lube oil additives by the condensation of an amine with an oxidized, e.g., ozonized, polymer.